1. Field of the Invention
The present invention relates to a rotary printing press with a printing cylinder which is provided on its exterior surface with a printing forme support and has a counter roller capable of exerting a printing pressure on a print web guided between the counter roller and the printing cylinder.
2. Description of Background and Material Information
Printing presses of the aforementioned type include, for example, rotogravure, letterpress, flatbed or offset rotary printing presses, depending on the printing forme support. In most cases, the counter roller is embodied as an impression cylinder, i.e., a soft printing cylinder, by means of which the printing pressure needed for transferring the print pattern from the printing cylinder is exerted on the print web, such as, for example, a paper web or plastic foil or the like. However, in rotary printing presses for simultaneous printing of both sides of a print web, the counter roller can also be another printing cylinder with a different printing forme support, wherein one of the two printing cylinders exerts a printing pressure on the other printing cylinder.
A requirement for such rotary printing presses is that the print quality must be sufficiently uniform across the entire width of the print web. However, this is difficult due to the difference in bending of the printing cylinder and the counter roller, as well as the appearance of resonant oscillations in the two rollers. For meeting this requirement, nevertheless, a rotary rotogravure printing press has been suggested in European Patent Application No. 0,439,822, published on Aug. 7, 1991, and in U.S. Pat. No. 4,058,877, issued on Nov. 22, 1977, the impression cylinder of which has a fixed support and a jacket rotatable around the latter. The impression cylinder jacket is supported on the support in the printing direction by a row of support elements disposed next to each other in the axial direction and each support element has, at least partially, an individually adjustable support force.
By means of the printing pressure of the support elements, which is controllable across the width, individually or in groups, it is possible to attain a printing pressure which is uniform to a large degree, or a desired print profile across the width of the print web. In spite of this, undesirable variations in print quality across the print width have occurred in rotary printing presses of greater width and higher printing pressure, even when using such an impression cylinder and in spite of the controllability of the printing pressure across the width of the web.